Gravetiller Festergeist

Swampwalk, Persist
When Gravetiller Festergeist enters the battlefield
each player mills 8 cards and gains 5 life.
Graveyards are shared among players.
(Effects and abilities that would work for one
player or that could be cast from the graveyard
by one player can be cast by all players.)
{r/g}{b/r}{b/g}: Exile a card from a graveyard.